Sumner Bar Swell Statistics, March: Surf with Light or Offshore Winds

This image shows only the swells directed at Sumner Bar that coincided with light winds or offshore conditions over a normal March and is based upon 2716 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. Green and yellow show increasing swell sizes and red shows highest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell occurs.

The diagram indicates that the most common swell direction, shown by the largest spokes, was E, whereas the the dominant wind blows from the N. The chart at the bottom shows the same thing but without direction information. For example, swells larger than 1.5 feet (0.5m) coincided with good wind conditions 3% of the time, equivalent to 1 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal March. Taking into account the fraction of these swells that coincided with predicted offshore winds, and given the fact that Sumner Bar is slightly protected from open water swells, we estimate that clean surf can be found at Sumner Bar about 3% of the time and that surf is blown out by onshore wind 7% of the time. This is means that we expect 3 days with waves in a typical March, of which 1 days should be clean enough to surf.

IMPORTANT: Beta version feature! Swell heights are open water values from NWW3. There is no attempt to model near-shore effects. Coastal wave heights will generally be less, especially if the break does not have unobstructed exposure to the open ocean.